How to send raw multitouch trackpad data under Mac OS X?

Question

The end goal is to take touch input from an iOS device, send it over a websocket, accept it on the Mac OS X side, and send it through the system so everything using the private multitouch framework to accept input sees the data as if it were normal multitouch trackpad data.

The synthesize sub-project under https://github.com/calftrail/Touch seems like a good place to start. However it seems like the developer created it with the intent of taking valid multitouch input (from a magic mouse when there was arbitrarily little software support from Mac OS X), and piping it as multitouch trackpad input. I need to create valid/acceptable multitouch trackpad out of thin air (with just sequences of touch locations, not real HID data).

In deep here. Help, someone. :)

Answer 1

Glad you found my TouchSynthesis subproject — I think it will let you do what you need, since internally it is split up as you want it. [Please note however that this code is GPL licensed, i.e. virally open source, unlike many Mac libraries.]

You can treat TouchSynthesis.m as example code for using the TouchEvents "library" which provides support for your specific question via one "simple" function: tl_CGEventCreateFromGesture

The basic gist is that tl_CGEventCreateFromGesture takes in a dictionary of gesture+touch data and will return a CGEvent that you can inject via Quartz Event Services into the system. A gesture event is required to send what becomes NSTouch data, but IIRC could be a fairly generic "gesture" type rather than zoom/pan/etc.

This is sort of a halfway-private solution: Apple support injecting CGEvents into the system [at least outside The Sandbox? …I've since lost interest in their platforms so haven't researched that one…] so that part is "fine", but the actual CGEvent I create is of an undocumented type, the format for which I had to figure out via hex dumps and some Darwin source code HID headers they shared. It's that work that "TouchEvents.m" implements — that's how Sesamouse could "create valid/acceptable multitouch trackpad out of thin air" — and it should already be separate from the private framework MultitouchSupport stuff that read in the Magic Mouse input.